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Added the Jarvis march in Coconut #734

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Sep 6, 2021
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40 changes: 40 additions & 0 deletions contents/jarvis_march/code/coconut/jarvis_march.coco
Original file line number Diff line number Diff line change
@@ -0,0 +1,40 @@
data point(x=0, y=0):
def __str__(self):
return f'({self.x}, {self.y})'

# Is the turn counter-clockwise?
def counter_clockwise(p1 is point, p2 is point, p3 is point) =
(p3.y - p1.y) * (p2.x - p1.x) >= (p2.y - p1.y) * (p3.x - p1.x)


def jarvis_march(gift: point[]) -> point[]:
point_on_hull = min(gift) # The leftmost point in the gift
hull = [point_on_hull] # It is guaranteed it will be on the hull.

while True:
# Candidate for the next point in the hull
endpoint = gift[0]
for p in gift:
if (endpoint == point_on_hull
or not counter_clockwise(p, hull[-1], endpoint)):
endpoint = p

point_on_hull = endpoint

# Check if the gift is completely covered.
if hull[0] == endpoint:
return hull
hull.append(point_on_hull)


if __name__ == '__main__':
test_gift = [
(-5, 2), (5, 7), (-6, -12), (-14, -14), (9, 9),
(-1, -1), (-10, 11), (-6, 15), (-6, -8), (15, -9),
(7, -7), (-2, -9), (6, -5), (0, 14), (2, 8)
] |> map$(t -> point(*t)) |> list
hull = jarvis_march(test_gift)

print("[#] The points in the hull are:")
for point in hull:
print(point)
2 changes: 2 additions & 0 deletions contents/jarvis_march/jarvis_march.md
Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,8 @@ Since this algorithm, there have been many other algorithms that have advanced t
[import, lang:"v"](code/v/jarvis.v)
{% sample lang="rust" %}
[import, lang:"rust"](code/rust/jarvis_march.rs)
{% sample lang="coco" %}
[import, lang:"coconut"](code/coconut/jarvis_march.coco)
{% endmethod %}

<script>
Expand Down